Researchers from Northeastern University and the National Institute of Standards and Technology (NIST) have improved the efficiency of clustered nanotubes used in solar cells to produce hydrogen by splitting water molecules.
By layering potassium on the surface of the nanotubes made of titanium dioxide and carbon, the photocatalyst can split hydrogen gas from water using ‘about one-third the electrical energy to produce the same amount of hydrogen as an equivalent array of potassium-free nanotubes.’
Rethinking the Possibilities at the Nanoscale
Energy is about manipulating the interactions of carbon, hydrogen, oxygen, metals, biological enzymes and sunlight.
When we design core enabling energy systems (e.g. catalysts, membranes, cathodes/anodes, et al) at the nanoscale (billionth of a meter) we find performance that is fundamentally different from the same systems designed at the 'microscale' (millionth of a meter).
Because smaller is better when it comes to manipulating molecules and light, the research teams used ‘tightly packed arrays of titania nanotubes’ with carbon that ‘helps titania absorb light in the visible spectrum.’ Arranging catalysts in the form of nanoscale-sized tubes increases the surface area of the catalyst which in turn increases the reactive area for splitting oxygen and hydrogen.
Hydrogen - Moving Beyond Hype and Skepticism
Metals, like platinum, palladium and nickel, play a key role as catatysts that change the quality of reactions of gases like carbon, hydrogen and oxygen.
Designing catalysts at the nanoscale (billionth of a meter) will help to improve interactions within fuel cells that convert chemical energy into electricity. But achieving precise control over nano-sized particles has been difficult.
Now Brown University researchers have designed fuel cell catalysts using palladium nanoparticles that have about 40 percent greater active surface area, and ‘remain intact four times longer’.
A New Binding Agent & Surface Area
The researchers have learned how to bind the 4.5 nanometer sized metal pieces to a carbon support platform using weak binding amino ligands that keep the nanoparticles separate. After they are set, the ligand links are ‘washed away’ without negatively changing the catalysts.
“This approach is very novel. It works,” said Vismadeb Mazumder, a graduate researcher who joined chemistry professor Shouheng Sun “It’s two times as active, meaning you need half the energy to catalyze. And it’s four times as stable. It just works better.”
MIT's Biomolecular Materials Group has advanced a technique of using 'genetically engineered viruses that first coat themselves with iron phosphate, then grab hold of carbon nanotubes to create a network of highly conductive material.'
This advanced 'bio-industrial' manufacturing process, which uses biological agents to assemble molecules, could help to evolve key energy material components (e.g. cathodes, anodes, membranes) used in batteries, fuel cells, solar cells and organic electronics (e.g. OLEDs).
Professors Angela Belcher and Michael Strano led the breakthrough bio-engineering work which can now use bacteriophage 'to build both the positively and negatively charged ends of a lithium-ion battery.' While the prototype was based on a typical 'coin cell battery', the team believes it can be adapted for 'thin film' organic electronic applications.
Energy = Interactions
Energy and Materials Science is about manipulating the assembly and interaction of molecules like carbon, hydrogen, oxygen and metals.
Today we are at the beginning of new eras of nanoscale materials science and bio-industrial processes that are certain to change the cost and efficiency equations within alternative energy and biomaterials. And we have a lot to learn about molecular assembly from Mother Nature's genetically driven virus/bacteria and plants. After all, the energy released from breaking the carbon-hydrogen bonds of coal (ancient ferns) and oil (ancient diatoms) was originally assembled by biology (with some help from geological pressures!). So why not tap this bio-industrial potential for building future energy components?
Scientists at the University of Liverpool and Durham University have developed a new carbon nanotube material that might evolve as a room temperature superconductor used to transmit electricity with no resistance or energy loss.
The use of football-shaped 'Carbon 60' fullerene molecules, or 'Bucky Balls', could change how we look at the quantum flow of electricity over long distance transmission lines as well as within medical equipment and 'molecular electronics'.
The idea of carbon-based electron transmission was widely promoted by carbon fullerene co-founder Rick Smalley (d. 2005) more than a decade ago as the 'quantum armchair wire'. The UK-based research suggests nanostructured carbon materials could evolve as room temperature superconductors.
Shape Matters: Carbon Buckyballs 'Squeezing' Electrons
Liverpool Professor Matt Rosseinsky explains: "Superconductivity is a phenomenon we are still trying to understand and particularly how it functions at high temperatures. Superconductors have a very complex atomic structure and are full of disorder. We made a material in powder form that was a non-conductor at room temperature and had a much simpler atomic structure, to allow us to control how freely electrons moved and test how we could manipulate the material to super-conduct."
Professor Kosmas Prassides, from Durham University, said: "At room pressure the electrons in the material were too far apart to super-conduct and so we 'squeezed' them together using equipment that increases the pressure inside the structure. We found that the change in the material was instantaneous – altering from a non-conductor to a superconductor. This allowed us to see the exact atomic structure at the point at which superconductivity occurred."
Trying to make the case that surface area is important to the future of energy is difficult. Surface area is not a sexy concept, and nearly impossible to fit into a media sound clip.
Barack Obama and John McCain do not call for energy systems with high surface area nano-catalysts. Instead they call for cheaper solar, and more powerful batteries and fuel cells for electric vehicles. Energy researchers would say – same thing!
Saying nanoparticles is a little better and certainly ripe for a media sound bite. But what if you could take a picture of molecules on a nanoparticle surface?
Now a group of researchers led by MIT have released the first composite atomic-scale images of the catalytic surface area of platinum-cobalt nanoparticles used in fuel cells. Their efforts could accelerate the development of electric fuel cell vehicles.
Surface area and the future of energy
Energy reactions occur when molecules interact. We simply capture the released energy. The cost and performance of batteries, fuel cells and capacitors depends on how molecules react (or do not interact) on tiny pieces of elements like lithium, carbon, titanium, and platinum.
The smaller the pieces, the more surface area, the more molecule interactions, the better the reaction. It also means lower cost because you use less material(e.g. expensive platinum).
If we can see the surface area of nanoscale designed catalysts we can design better (and cheaper) catalysts used in fuel cells.
First images of nanoparticle platinum-cobalt surface
Today a group of researchers from MIT, UT-Austin and ORNL has released images of nanoscale surface by using a technique known as Scanning Transmission Electron Microscopy.
The researchers analyzed platinum and cobalt nanoparticles to understand why the performance of a combined catalyst was more reactive than simply using platinum alone.
Now the researchers can propose and test theories to why the material is so reactive. If researchers can design catalysts with less platinum, the cost of fuel cells could drop dramatically.
The same principle of surface area applies to building better batteries and capacitors. If we can apply this imaging technique across all devices, we could accelerate commercialization of highly efficient energy storage systems.
Scientists at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory have taken the first-ever glimpse of nanoscale catalysts in action.
Why should we care about catalysts?
The future of clean abundant energy depends on our ability to lower the costs of chemical reactions in energy conversions involving light, hydrogen, carbon, and oxygen. These are the foundations of most energy systems, and basis for developing ‘green chemistry’ that avoid harmful byproducts.
If we want to create low cost solar cells or improve batteries and hydrogen fuel cells, we must advance our knowledge and nano-engineering of catalysts. If we want to reduce the impact of harmful emissions from coal, oil and natural gas, we must turn to catalysts.
Nanoscale design of shapes
Catalysts speed up chemical reactions. At the most basic level shape matters. To improve performance we can design catalysts at the ‘nanoscale’ (billionth of the meter) to change properties of low cost abundant elements rather than rely on expensive precious metals. At the nanoscale we design higher surface area to increase chances of molecules reacting, and we can design shapes so that they have high selectivity to deal with a certain type of molecules (e.g. capturing sulfur, releasing hydrogen).
Up until now, scientists have only dealt with snapshot images of catalysts before or after. Never live, in action. Now Berkeley scientists have changed the game. “By watching catalysts change in real time, we can possibly design smart catalysts that optimally change as a reaction evolves,” Gabor Somorjai, a renowned surface science and catalysis expert.
Berkeley researchers are confident that catalysts can be designed to decrease the harmful effects of pollutants, improve performance of energy storage systems like batteries and hydrogen fuel cells and create ‘greener’ liquid fuels and feedstocks associated with ‘green chemistry’ in which waste byproducts are minimized.
What happened? Video explanation?
The nanoscale design of basic energy components is once again revealing new solutions to the historical problems of high cost alternative energy systems.
Materials scientists from Washington University in St. Louis and Brookhaven National Laboratory have designed a nanostructured bimetallic (platinum and palladium) fuel cell catalyst that is 'efficient, robust and two-to-five times more effective than existing commercial catalysts.'
Fuel cells are important as 21st century 'power plants' that produce electricity on demand without a grid connection. Fuel cells can be designed as small as a AA battery (for portable gadgets), a breadbox (for electric vehicles), a small refrigerator (for home power) or the size of a small room (for utility power generation).
Commercialization of fuel cells depends on our ability to lower the costs of core membranes (MEAs) that convert chemical energy into electricity.
So what is the way forward? Nanostructured design of key membrane components.
Rethinking Surface Area & Shape
Team leader Professor Younan Xia explains the importance of the breakthrough: "There are two ways to make a more effective catalyst," Xia says. "One is to control the size, making it smaller, which gives the catalyst a higher specific surface area on a mass basis. Another is to change the arrangement of atoms on the surface. We did both. You can have a square or hexagonal arrangement for the surface atoms. We chose the hexagonal lattice because people have found that it's twice as good as the square one for the oxygen reduction reaction (which determines the electrical current generated)."
To reduce costs and improve performance the team experimented with new core and branching structures. The catalyst has a core made of palladium which branching arms (‘dendrites’) of platinum that are seven nano-meters long.
According to Xia's team release: ‘At room temperature operation the team’s catalyst was two-and-a-half times more effective per platinum mass for this process than the state of the art commercial platinum catalyst and five times more active than the other popular commercial catalyst. At 60 degrees C (the typical operation temperature of a fuel cell), the performance almost meets the targets set by the U.S. Department of Energy.’
The next step for the team?
Integrating gold as a third metal catalyst to deal with the problem of carbon molecules that reduces performance by binding and blocking valuable surface area.
MIT Technology Review has featured a research breakthrough in platinum free fuel cells that could significantly reduce costs for a unique type of fuel cell energy conversion devices.
A Wuhan University team led by Professor Lin Zhuang has developed an Alkaline Fuel Cell (AFC) using a new hydroxyl ion electrolyte that uses low cost nickel catalyst materials to react hydrogen and oxygen to create electrical current, heat and water.
NASA has used alkaline fuel cells (AFC) in space missions since the 1960s, but these types of fuel cells are not likely to be used in automobile or portable devices. They might best be suited for onsite power generation, which is still an enormous market. AFCs use a water-based electrolye that lets postive charged molecules pass, diverting negative charges into the current. They are very efficient (up to 70%) but do have their downsides. If the team of researchers can increase the protoype's 'modest' electricity output (50 milliwatts/sq centimeter at 60 ºC) it could help bring low cost alkaline fuel cells to market.
Why is this important to the future of energy?
Understanding Fuel Cells & The Hype Cycle